In some oilfield applications, pump assemblies are used to pump a fluid from the surface into the wellbore at high pressure. Such applications include hydraulic fracturing, cementing, and pumping through coiled tubing, among other applications. In the example of a hydraulic fracturing operation, a multi-pump assembly is often employed to direct an abrasive-containing fluid, i.e., fracturing fluid, through a wellbore and into targeted regions of the wellbore to create side fractures in the wellbore.
The fracturing fluid is typically formed at the wellsite in two steps, using two different assemblies. The first assembly, which generally contains a gel mixer, receives a process fluid and mixes the process fluid with a gelling agent (e.g., guar) and/or any other substances that may be desired. The gelled process fluid is then moved (pumped) to a blender, where it is blended with a proppant. The proppant serves to assist in the opening of the fractures, and also keeping the fractures open after deployment of the fluid is complete. The fluid is then pumped down into the wellbore, using the multi-pump assembly. Additionally, other types of dry additives and liquid additives at desired points in the fluids flow.
Each of these assemblies—gel mixing, proppant blending, and multi-pump—can include drivers, such as electric motors and/or other moving parts, which generate heat due to inefficiencies. To maintain acceptable operating conditions, this heat is offloaded to a heat sink. The simplest way to remove heat is with an air-cooled radiator, since the transfer medium and heat sink (air) are freely available. In contrast, liquid sources and heat sinks generally are not freely available, especially on land. However, air-cooled radiators require additional moving parts, which introduce a parasitic load on the assemblies, i.e., a load needed to keep the equipment cool but not otherwise contributing to the operation.
Further, air-cooled radiators are large, heavy, and noisy. Each of these considerations may impact the surrounding environment, increase footprint, and may impede portability, usually requiring permits for overweight and/or oversized equipment, and more restrictions on possible journey routes. For offshore applications, weight and size both come at a premium, and being lighter and smaller may offer a competitive advantage. Further, in offshore installations, large radiators may need to be remotely installed from the primary equipment (e.g., a few decks above where the primary equipment is installed) due to their size, which can require additional coolant and hydraulic or electric lines. Additionally, air-cooled radiators may be subject to extreme ambient temperatures and/or altitudes, which may limit their efficacy.